Molecular Communication (MC) is a nanoscale interaction paradigm inspired by the natural ability of cells in biology to communicate through the processing, exchange, and transduction of information by biochemical reactions of molecules. The design and modeling of MC systems is the first step towards future applications based on the engineering of communication systems in biology. In this paper, a bandpass filter based on a specific type of biochemical reactions in cell communication, namely, signaling kinase cascade, is proposed for an MC receiver in a diffusion-based MC scenario. In particular, under the commonly accepted weak activation assumption, these biochemical reactions can be analytically modeled through linear systems theory. The characterization of the proposed filter, and the corresponding numerical results, demonstrate its passband properties, and its suitability for extracting signals in different frequency bands coming from different molecular transmitters.